package NowCoderHuaWei;

import java.util.*;
public class Test10{
    public static void main(String[] args)
    {
        Scanner in=new Scanner(System.in);
        HashSet<Character> hs=new HashSet<Character>();
        while(in.hasNext())
        {
        	hs.clear();
            String str=in.nextLine();
            for(int i=0;i<str.length();i++)
            {
                hs.add(str.charAt(i));
            }
            System.out.println(hs.size());
        }
        in.close();
    }
}